Psychoneuroendocrinology is the clinical study of hormone fluctuations and their relationship to human behavior. It may be viewed from the perspective of psychiatry, where in certain mood disorders, there are associated neuroendocrine or hormonal changes affecting the brain. It may also be viewed from the perspective of endocrinology, where certain endocrine disorders can be associated with negative health outcomes and psychiatric illness. Brain dysfunctions associated with the hypothalamus-pituitary-adrenal axis HPA axis can affect the endocrine system, which in turn can result in physiological and psychological symptoms. This complex blend of psychiatry, psychology, neurology, biochemistry, and endocrinology is needed to comprehensively understand and treat symptoms related to the brain, endocrine system (hormones), and psychological health. (see neurobiological brain disorder). Disorders Premenstrual Syndrome (PMS) and Premenstrual Dysphoric Disorder Premenstrual syndrome is a mood disorder which occurs recurrently in the late luteal phase of the menstrual cycle and remits within the first day or two after the onset of menstruation. Symptoms include depression, irritability, anxiety, insomnia, bloating, breast tenderness, cramping, and headaches. About 5-9% of women of child-bearing age meet the DSM-IV criteria for PMDD. In some women, end-of-cycle worsening actually represents "menstrual magnification" of an underlying mood disorder. Premenstrual dysphoric disorder can be treated cyclically with hormonal oral contraceptives, or with antidepressants, which may be used continuously or only during the late luteal phase. Selective serotonin reuptake inhibitors, or SSRIs, have been found to be effective in the treatment of PMDD. Physical symptoms can be affected by the intake of caffeine, salt, alcohol, and nicotine, so the use of these substances should be monitored and potentially decreased. Sleep hygiene measures, exercise, relaxation therapy, and cognitive behavioral therapy are all potentially effective non-medication strategies for milder symptoms. Postpartum Depression (PPD) Postpartum psychiatric disorders typically divided into three categories: (1) postpartum blues (2) postpartum depression and (3) postpartum psychosis. It may be useful to conceptualize these disorders as existing along a continuum, where postpartum blues is the mildest and postpartum psychosis the most severe form of postpartum psychiatric illness. Up to 85% of women experience postpartum blues during the first two weeks after delivery. Symptoms include tearfulness, mood lability, irritability, and anxiety. These symptoms typically peak between postpartum days 5–7, and remit spontaneously within two weeks postpartum, so active treatment is not required. Postpartum depression refers to a major depressive episode occurring following childbirth. While women can become depressed at different points in time